What HP is safe for aircooled engine???

[empire0007]

I have heard that anything over 550WHP for aircooler engine will damage the motor, unless you have the flat fan, like the 935 engine? Do any of you guys run that kind of power on track? If so how much power and how long has the engine lasted? The head is the issue from my understanding?

[HawgRyder]

I think you missed the point.
As long as the parts inside the engine are stressed for the HP and torque...the sky is the limit.
The next consideration....cooling...you must keep it cool troughout the RPM range.
You can NEVER overbuild an engine!!
That is to say...you can buy the best parts that your wallet will allow (even over spend) and be perfectly happy with the result.
BUT....if you cheap out on any part...that will be the one to break.
So...550...? Sure
Even 1050 is possible...but once again...good parts...and great cooling!
Bob

[Edelweiss]

Originally Posted by HawgRyder

I think you missed the point.
As long as the parts inside the engine are stressed for the HP and torque...the sky is the limit.
The next consideration....cooling...you must keep it cool troughout the RPM range.
You can NEVER overbuild an engine!!
That is to say...you can buy the best parts that your wallet will allow (even over spend) and be perfectly happy with the result.
BUT....if you cheap out on any part...that will be the one to break.
So...550...? Sure
Even 1050 is possible...but once again...good parts...and great cooling!
Bob

I would agree 100 % !

I know several bullet proof, and German Autobahn proven, engines that do 700 plus hp.

No flat fan no problems.

Keep ignition and fuel supply under control, make use of internal cooling and you are fine.

Most important, as Bob said already, is the quality of the parts you use.

Here you have to be very specific about the pistons.

A lot that can handle 400 m but just a few that can last full load for a longer while.

Go always for the best you can find and build up knowledge about it.

Look what the good ones use.

For example you will never find a Wõssner piston inside a Porsche works or Ruf engine.

Best reg.

Dirk

[turbobrat930]

There are several 700+HP cars just on the 930 forums here....

[empire0007]

Mike wrote:
thank you for responding. I do have a solid engine. It's a 3.8 TT, 993 RSR Motorsports turbo Piston/Cylinders. Asco 993 welded heads, GT2 EVO Cams. Pauter Rods, ARP, much much more into it. All machine work was done by ASCO Motorsports, the engine is built by 911Design.

the engine builder has detuned the car at this point. So far At 1.0 bar it's putting out 630whp & 572 torque. Very conversative with the timming and we changed the compression down to 7.5-1.

911Desgin is say's anything over 550whp will not be safe, as it will damage the engine.

I have methanol setup as well, which we are not even going to use, as we can easy get up to 700whp without any issue. The engine can produce lot's of power, but it's the heat that we are concerned.

Would like the input.

[empire0007]

http://https://www.youtube.com/watch?v=3W9nPlRqNo8

https://www.youtube.com/watch?v=3W9nPlRqNo8

[dos531]

Originally Posted by empire0007

Mike wrote:
thank you for responding. I do have a solid engine. It's a 3.8 TT, 993 RSR Motorsports turbo Piston/Cylinders. Asco 993 welded heads, GT2 EVO Cams. Pauter Rods, ARP, much much more into it. All machine work was done by ASCO Motorsports, the engine is built by 911Design.

the engine builder has detuned the car at this point. So far At 1.0 bar it's putting out 630whp & 572 torque. Very conversative with the timming and we changed the compression down to 7.5-1.

911Desgin is say's anything over 550whp will not be safe, as it will damage the engine.

I have methanol setup as well, which we are not even going to use, as we can easy get up to 700whp without any issue. The engine can produce lot's of power, but it's the heat that we are concerned.

Would like the input.

I dont have experience at those power levels, but if you're worried about heat, the water methanol injection is proven to lower CHT significantly. Even if you dont need the octane boost, why wouldnt you use it for the cooling and for an extra margin of safety?

['76 911S 3.0]

I've spent a lot of time over at 911 Design, Loren is very knowledgeable and a good guy. He's been in the industry a long time and any advice he gives you is solid.

I think what Loren is getting at is reliability and longevity of the engine. He's recommending a power level that will ensure that your engine internals are not stressed to their limits and your engine will survive for a while.

[Matt Monson]

Originally Posted by empire0007

Mike wrote:
thank you for responding. I do have a solid engine. It's a 3.8 TT, 993 RSR Motorsports turbo Piston/Cylinders. Asco 993 welded heads, GT2 EVO Cams. Pauter Rods, ARP, much much more into it. All machine work was done by ASCO Motorsports, the engine is built by 911Design.

the engine builder has detuned the car at this point. So far At 1.0 bar it's putting out 630whp & 572 torque. Very conversative with the timming and we changed the compression down to 7.5-1.

911Desgin is say's anything over 550whp will not be safe, as it will damage the engine.

I have methanol setup as well, which we are not even going to use, as we can easy get up to 700whp without any issue. The engine can produce lot's of power, but it's the heat that we are concerned.

Would like the input.

Loren is a very good customer of mine, and I hesitate to say anything that might be construed as negative. That said, Eddie Bello is also a customer and his 964 drag turbo makes 1200 whp. The engine is rarely the issue. The tuner has a shyte-ton to do with it. Kirk, Loren's top mechanic, who most likely built your engine, can build you a kick arse engine, but if you don't have the right tuner you are dead in the water.

They are being respectfully conservative. Wait until you start breaking gearboxes at your current levels. That's the 2nd part of the equation.

But you have a solid foundation to build a kick arse building. Don't worry too much about the limit they set. That's their limit, not the actual limit of your existing build.

[HawgRyder]

The guys brought up a very important point....the rest of the power train!
If you make BIG HP you have to transfer that to the pavement.
So...clutch...gearbox...half shafts....bearings...and even wheels and tires become a problem.
When we were racing an A/FX Ford ... the gearbox ended up with 9310 Nickalloy gears...special shafts...and even a special case.
The clutch gained several disks.
The drive shaft changed to one of large size with huge Spicer joints.
We ran 24" wide rubber on the rear (which necessitated a change in body work).
So HP and torque is just the start of the slippery slope...LOL
BTW...how much did you WIN on the lottery?
Bob

[JV911SYDNEY]

Originally Posted by empire0007

What HP is safe for aircooled engine???

That's a bit like asking, how long is a piece of string?

It'll handle what it, and everything around it, is built to handle.

[empire0007]

That is exactly correct, but just waned to see if running at 1.0 not in track with that kind of power, anyone has any issue.

Originally Posted by '76 911S 3.0

I've spent a lot of time over at 911 Design, Loren is very knowledgeable and a good guy. He's been in the industry a long time and any advice he gives you is solid.

I think what Loren is getting at is reliability and longevity of the engine. He's recommending a power level that will ensure that your engine internals are not stressed to their limits and your engine will survive for a while.

[empire0007]

Mike wrote:
That's also been done. I didn't want to go over everything that we did. We have spent over 80K on this engine, tranny and computer. It has the best parts that money could buy except with not going to Motec. That is the only this, but REDLINE is a very good system as well.

Originally Posted by HawgRyder

The guys brought up a very important point....the rest of the power train!
If you make BIG HP you have to transfer that to the pavement.
So...clutch...gearbox...half shafts....bearings...and even wheels and tires become a problem.
When we were racing an A/FX Ford ... the gearbox ended up with 9310 Nickalloy gears...special shafts...and even a special case.
The clutch gained several disks.
The drive shaft changed to one of large size with huge Spicer joints.
We ran 24" wide rubber on the rear (which necessitated a change in body work).
So HP and torque is just the start of the slippery slope...LOL
BTW...how much did you WIN on the lottery?
Bob

[Matt Monson]

Take a look at Pat Williams turbo racecars. He's got about 4 of them (personal and shop cars) that are in the 600-750whp range. They all run GT class in PCA and have for years. A couple are 930s, and a couple are 993 turbo conversions. A Google search will bring them up. One of them holds a track record at Road Atlanta. There is a YouTube video of the record lap.

[empire0007]

Matt how would a good person to tune this car. I would like to have a second individual go over the tune as well. I know the tune is a magor factor and i have already experinced it not long ago, blowing up the motor on a fresh built.

Originally Posted by Matt Monson

Loren is a very good customer of mine, and I hesitate to say anything that might be construed as negative. That said, Eddie Bello is also a customer and his 964 drag turbo makes 1200 whp. The engine is rarely the issue. The tuner has a shyte-ton to do with it. Kirk, Loren's top mechanic, who most likely built your engine, can build you a kick arse engine, but if you don't have the right tuner you are dead in the water.

They are being respectfully conservative. Wait until you start breaking gearboxes at your current levels. That's the 2nd part of the equation.

But you have a solid foundation to build a kick arse building. Don't worry too much about the limit they set. That's their limit, not the actual limit of your existing build.

[txhokie4life]

What is a reasonable number for NA air cooled engines?

I have a MOTEC48 and FI ITB's and Flowmaster headers with otherwise
stock 964 engine. With the current tune -- this is 251hp/209tq.

I'm looking to build out a 964/993 based 3.8 engine for 100% track use.
Reliability is crucial. What HP should I expect, any pointers for CAMs and
other components? Budget conscious, but but not at the expense of reliability.


Mike

[Steve@Rennsport]

Originally Posted by txhokie4life

What is a reasonable number for NA air cooled engines?

I have a MOTEC48 and FI ITB's and Flowmaster headers with otherwise
stock 964 engine. With the current tune -- this is 251hp/209tq.

I'm looking to build out a 964/993 based 3.8 engine for 100% track use.
Reliability is crucial. What HP should I expect, any pointers for CAMs and
other components? Budget conscious, but but not at the expense of reliability.


Mike

Hi Mike,

The VERY first question I ask prospective clients (after discussing what they want) is; "Whats your budget?". This is, after all, what defines the reality and scope of the build in terms of whats possible and what isn't. Answer that, and I can help.

We can get 450+ BHP from a naturally aspirated engine, however this not inexpensive to do and its a 25-50 hr engine.

[txhokie4life]

Originally Posted by Steve@Rennsport

Hi Mike,

The VERY first question I ask prospective clients (after discussing what they want) is; "Whats your budget?". This is, after all, what defines the reality and scope of the build in terms of whats possible and what isn't. Answer that, and I can help.

We can get 450+ BHP from a naturally aspirated engine, however this not inexpensive to do and its a 25-50 hr engine.

Good Question Steve: To me it's hard to come up with a budget.
I'm an engineer -- so everything is a trade-off to me.

My take is I will generally spend what it takes to do it right with a budget in mind,
giving the perceived benefit/cost.

When I got the RSR == the 3.8 was in rubbermaid boxes. The PO had melted the heads and had piston slap issues.

I chose to source a base 964 as a starter engine -- it was the fastest, cheapest (relatively) way to get on the track and learn how to drive the RSR.
I had to do a top end rebuild and used the 993 springs -- but otherwise left the engine as is.

Now I'm thinking about building out the 3.8 engine and considering my options.
The labor is free -- or free enough, as I will build the engine, and/or have a friend help out. Considering what I have to start with -- I think ~$10k is the budget for parts.

I'd like to reliably be in the 350-375HP to the wheels range. I'd like to think of this as a 100 hr engine (do it once, do it right, be done with it). I'll be lucky to run this car 4 weekends a year.

I already have a weekend track car -- I have an endurance race car. This would be for COTA events (since its local), and possible occasional PCA Club Racing.

With that in mind:

I'm scrapping the pistons, but the jugs (3.8 mahles) I have had inspected multiple times with good reports, I will keep.

I'm considering using E85 for a couple reasons. Potential to run higher compression, a little bit of cooling effect with the increased flow, and economics relative to race gas.
So I'm leaning for 12.5:1 pistons.

The heads have been redone (and thus not part of the budget) -- I will probably stay with the 993 valves, but upgrade the valve springs and retainers. I'll splurge here as that gives me head room for RPMs (minor shifting issues :-)

The engine came with Carilla rods -- and I see no reason to replace them, they
are in perfect condition.

For reliability for the $$ I will go with improved studs and rod bolts.

I'm still trying to determine my bearing choices. The current discussions about Glyco
have me nervous -- but I don't know what the alternatives are.

Cams are an option, one that I'm not too familiar with. What I have are either stock 964 or 993 (I need to verify).

The engine mates up with a 5 disc Tilton clutch and a G50 with straight cut gears.
Its a 100% track car.

So that is where I'm at at the moment. Researching for a winter build up.

Here's a picture of the 964 based engine I'm running now with the go fast parts bolted up.

There is nothing fundamentally wrong with the 964 setup -- it just runs out of steam on the long COTA straights -)

Mike

[Matt Monson]

Matt how would a good person to tune this car. I would like to have a second individual go over the tune as well. I know the tune is a magor factor and i have already experinced it not long ago, blowing up the motor on a fresh built.>

Betim at BBI.

[JV911SYDNEY]

Originally Posted by txhokie4life

I think ~$10k is the budget for parts....

I'm scrapping the pistons, but the jugs (3.8 mahles) I have had inspected multiple times with good reports, I will keep....

So I'm leaning for 12.5:1 pistons…

but upgrade the valve springs and retainers...

The engine came with Carilla rods -- and I see no reason to replace them, they are in perfect condition....

For reliability for the $$ I will go with improved studs and rod bolts....

Cams are an option, one that I'm not too familiar with. What I have are either stock 964 or 993 (I need to verify)....

You’re on the right track with your pistons, rods, valve springs, studs etc assuming everything you are reusing is in spec. The $10k budget and 350-375rwhp however does not add up. 300 is closer to the mark given the components and budget you have. As Steve, in classic understatement said, 450hp (370rwhp) is not inexpensive…it’s GT3 crank & plenum, Ti rods and billet heads territory!

As for cams, speak directly to a guru such as Elgin. Tell him your specs and he’ll come up with something nice for you. None of this off the shelf, 20 year old design business. And find a good tuner and get some dyno time.

oh and you might want to look at changing gear ratios if you haven't already